The Study And Application Of Amylase And Sodium Persulfate In Desizing Process Of STARCH/PVA Mixed-Size

Starch and PVA mixed size is still adopted by numerous textile mills due to its stiff film, convenient procedure and low price. However, there are two main problems in desizing PVA, the remaining size is likely to have serious negative effect on printing and PVA is regarded to cause environment pollution due to its low biodegradability. In recent year, reducing pollution and protecting environment which we live in is not uncommon among people’s daily life, in this case it is the development trend in desizing process that decreasing consumption of chemicals and water and side effect on environment thereby achieving cleaner production.The mechanism of amylase in desizing is that it can decompose starch and reduce molecular weight and solution viscosity rapidly, which benefits the following washing process. Oxidant, which oxides chemical size and triggers macromolecule degradation, leading to increase water-soluble ability and reduce bath viscosity, can also been used in desizing procedure. Combination of amylase and oxidant can finish desizing under relatively low temperature and decompose macromolecule especially PVA size to reduce environment pollution and effluent-treating burden.This research firstly takes PVA size as the object of study and size degradation level can be determined by weight difference before and after NaOH,Na2S2O8and H2O2treatment with the analysis of solution viscosity change. The result shows that both Na2S2O8and H2O2can reduce size viscosity effectively and degrade size partly. It should point that Na2S2O8performs better during desizing process and can be easily used in industry for its stable in storage and transportation.Secondly, we regard PVA size film as target, emphatically analyzing technological conditios of Na2S2O8which affects its property on dissolving and degrading PVA. Through the analysis of every factor’s influence on PVA weight loss rate and degradation rate based on single factor experiment, concludes could be drawn that under below condition Na2S2O8concentration6g/L,NaOH concentration3g/L, temperature60℃, time60min, weight loss and decomposition rate can reached up to73.6%and84.7%respectively.Furthermore, the desizing of mixed size film will use amylase and Na2S2O8by different process to choose the best.It is concluded that one bath two stage process is the best, which is first amylase and then Na2S2O8.The enzyme desizing was amylase concentration6mL/L, SAA concentration2g/L, and Na2S2O8desizing was Na2S2O8concentration6g/L, NaOH concentration3g/L, temperature6O℃.All the time is70min.Finally, the research results will be applied to cotton textile sizeing with starch and PVA. The characterization of desizing effect can use desizing rate, whiteness, capillary effect and tearing strength.It conclude that useing amylase/Na2S2O8, the desizing rate is98.3%and PVA degradation rate is77.6%,follow with low strength loss.In conclusion, the degradation of mixed size film can provide theory basis for cold-pad-batch desizing process.Amylase desizing belongs to cleaner production, it can reduce the dosage of alkali. It has a profound significance to improve the degradation rate of mixed size, reduce COD and energy consumption.